Non-constant anodization current effects on spectra of porous silicon LEDs

Porous silicon (PoSi) LEDs are today under investigation for integration of optoelectronic silicon devices with standard microelectronic circuits. The electrical and optical properties of these devices depend on the anodization parameters (current density and time) of the PoSi formation process. However, a constant anodization current is generally used to fabricate the active PoSi layer of LEDs, and only few works exist in which a non-constant anodization current is reported. In this work, a study of the anodization current effects on the electroluminescence (EL) spectra of PoSi LEDs having around 0.1% of external quantum efficiency is presented. Several anodization current waveforms (constant, linear, triangular, and trapezoidal) were used to fabricate layers with different mechanical and optical properties. EL spectra of fabricated devices are reported and discussed.